feat(update): update the backend like nodes via quadlet restart [CI]

backend/tests/MoShiro.Backend.Tests/BackendFixture.cs

@@ -21,6 +21,15 @@ internal static class Defaults
 /// 在真实的 Kestrel 端口上启动整个后端（真实的 SQLite 与段文件，只是用临时目录和较快的轮询），
 /// 并提供管理员客户端（Bearer 令牌）和假 Agent。
 /// </summary>
+public sealed class RecordingBackendRestart : MoShiro.Backend.Application.IBackendRestart
+{
+    private int _count;
+
+    public int Count => Volatile.Read(ref _count);
+
+    public void Request() => Interlocked.Increment(ref _count);
+}
+
 public class BackendFixture : IAsyncLifetime
 {
     public const string AdminUser = "admin";
@@ -47,6 +56,9 @@ public class BackendFixture : IAsyncLifetime
     /// <summary>带 admin 作用域的 API 令牌的客户端。</summary>
     public HttpClient Admin { get; private set; } = null!;
 
+    /// <summary>Backend 更新确认之后「请求退出」的次数（测试里不真的退出）。</summary>
+    public RecordingBackendRestart Restarts { get; } = new();
+
     public IServiceProvider Services => App.Services;
 
     /// <summary>夹具创建的默认 Probe：合成块（<see cref="ChunkFactory"/>）和单线路的查询都用它。</summary>
@@ -267,7 +279,11 @@ public class BackendFixture : IAsyncLifetime
                 options.NodeImageRegistry = string.Empty; // 同理：后台不去真实的镜像仓库取清单
                 options.PhaseDurationScale = 0.2; // 端到端测试里 connect、hold 这些固定 30 秒的阶段缩成 6 秒
             },
-            configureServices: services => services.AddSingleton<MoShiro.Backend.Application.IReleaseKey>(TestReleaseKey.Instance)); // 登记清单要验发布签名：测试用自己的密钥签
+            configureServices: services =>
+            {
+                services.AddSingleton<MoShiro.Backend.Application.IReleaseKey>(TestReleaseKey.Instance); // 登记清单要验发布签名：测试用自己的密钥签
+                services.AddSingleton<MoShiro.Backend.Application.IBackendRestart>(Restarts); // 更新确认之后只记一笔，不真的退出
+            });
         await App.StartAsync();
         string address = App.Services.GetRequiredService<IServer>().Features.Get<IServerAddressesFeature>()!.Addresses.First();
         BaseAddress = new Uri(address);